SHORT COMMUNICATIONS

ORNITOLOGIA NEOTROPICAL 10: 91–94, 1999 © The Neotropical Ornithological Society

SINGLE NESTLING CARE AND MALE ABANDONING IN VARIABLE ANTSHRIKES CAERULESCENS, WITH NOTES ON EXCESS ROADSIDE CLEARING

Yoshika Oniki & Edwin O. Willis

Departamento de Zoologia, UNESP, 13506-900 Rio Claro, SP., Brazil

Key words: Antshrikes, monogamy, nesting, roadsides, Thamnophilus caerulescens.

INTRODUCTION in a mossy-outside pendent cup nest, 1.8 m high in a Tibouchina sp. bush by the east road Antshrikes (Family Thamnophilidae, Thamno- of Augusto Ruschi (Nova Lombardia) Biolog- philus) are among the commonest understory ical Reserve, at about 850 m elevation and in many neotropical forests and wood- 19º55'S, 40º34'W, in the serras near Santa Ter- lands, with one second-growth species (the esa, Espírito Santo. The species does not Barred Antshrike, T. doliatus) even invading occur in tall forest there, and this was a tall suburbs in southern Brazil (MS). Nest build- second-growth former clearing by a small ing, incubation and care of young is per- creek. On 19 January, the nest contained one formed rather equally by male and female egg and one tiny young, and the male was antshrikes (Oniki 1975), as in other genera of brooding. Oniki made observations from a the family, even though they are often sexually car by the road, on 21, 22, 24 and 27 January, dimorphic. In southeastern Brazil, between for 23 h and 10 min. She checked weights and January and March 1995, we had the opportu- measurements several days. Only a single nity to study nestling and fledgling care at a nestling was present, the unhatched egg being nest of Variable Antshrike (T. caerulescens), a collected on 22 January and the nest later. species in which males and females are not so different in plumage. Several well-marked OBSERVATIONS races range in subtropical woodland and sec- ond growth from southeastern Brazil to the On 21 January, the nest was 8 cm high (plus (Meyer de Schauensee 1970). 7.5 cm hanging moss), 10 cm across with an inner cup diameter of 9 cm and inner height METHODS of 5 cm (7 cm to fork). The young was 3–4 days old (5.6 g, wing pinfeathers 2 mm, tracts On 16 January, Willis found a male incubating dark gray, bill 6 mm, tarsus 10 mm; eyes

91 GENERAL BIOLOGY closed; pale yellow gape, pink skin). The egg flew to the woods behind the nest, hopped in weighed 3.1 g, 23.5 x 17 mm, and was pink- the undergrowth nearby, then flew to the ish-white with large red-brown spots at the woods across the road. large end, plus a few elsewhere. On 22 Janu- After feeding or arriving, the adult looked ary at 17:12 h, the young weighed 9 g, with a down inside or below the nest, sometimes bill 8 mm, tarsus 15 mm, wing 6.5 mm. It poking in the nest material for ectoparasites peeped a lot on this date. By 24 January the for up to several minutes. When there was same measurements were 13.4 g, bill 8 mm, a fecal sac after feeding, the adult ate it and tarsus 19, wing 15, peeping. On 27 January, then looked carefully inside the nest, some- 15.1 g, bill 10, tarsus 21, wing 26 (feather 6), times making a sudden movement forward as spotted with whitish. The adults spread and if it saw an ectoparasite; looking again care- flicked their tails upward (to the line of the fully, lowering the body, it looked about again body) slowly, calling "ah!” faintly (sounds and hopped to sit inside nest. recorded, as of young) near the ground, when Once, on 21 January, the male and female they saw Oniki returning the peeping young came to the nest edge with food together; the to the nest on the 27th. male fed at 13:21 h and pecked down in the The female seemed shy the first day of nest. When the female arrived, he pecked and observations (8:36–18:15 h) and wound up ate bits of food from her beak, giving the rest spending less time on the nest by day than the to the nestling, and sat on the nest at 13:24 h. male, 187 min to his 283 (not counting her The female stayed on the nest edge, and the time 17:38 h on, when she went on for the male left at 13:27 h; she poked in the nest 10 s night), totalling 87% of the day. She ate the before brooding. small green prey she brought at 08:55 h and On the 21st, the male pounded a green left; at 10:42 h, she fed the young but left after prey item on a limb at 09:21 h but went to the the male had sat from 09:21 to 10:36 h with- nest without food; on his 11:38 to 12:36 h out feeding. However, both birds foraged visit, he seemed to bring no food; he fed on along the road and she returned with a gray four other visits, but tried to feed 16 times in small caterpillar, sitting from 10:56 to 11:34 h, 1 min and finally ate the food himself before apparently less wary. On other days, the brooding at 15:22 h. Besides the 08:55 h visit female brooded young more than did the without feeding, the female came without male and, on 27 January, she alone brooded food for a 12:30 to 12:45 h brooding visit; she for 59 min, or 43% of observations (13:04– fed on six more visits, including at 17:38 h 16:20), on the last three of her six visits. when on for the night. At 17:46 h on the next When brooding, the adult in the nest day, she went on without feeding. On 24 Janu- remained very alert with head high and bill ary, several male and female visits were with widely open due to heat; but when a person food, but the female left from 18:11 to 18:17 walked nearby it sat very low in the nest with h and returned without food, after feeding at only the tail visible. Since the nest was next to 17:20 h and again at 17:30 h, when she went the road, each time a truck or jeep passed, on the nest. On the afternoon of 27 January, raising a lot of dust or shaking the nest, the the male fed the nestling only once (at 14:47 brooding adult crouched low. When about to h), but the female fed six times. leave the nest after a session, it became more Since the brooding on the nest usu- alert, opened the tail feathers, stretched its ally left only when the other arrived, time on neck forward or looked down below the nest the nest depended on the partner's effort at and hopped out flying forward. A few times it food providing, except for such brief visits as

92 SHORT COMMUNICATIONS that of the female at 17:20 h. The male had Here, we suggest, based on these two spent 75, 58 and 84 min waiting and brood- nests, that a single nestling may not need as ing on 21 January, but on 21 and 24 January, much food as two parents can bring, for even the female had to wait 96 (from 13:27 to during brooding some visits of both sexes of 15:03 h) min and 51 (from 14:25 to 15:16 h) the antshrike were without food. Having only min for him to return. one sex feeding, rather than two birds alter- The young was gone when the nest was nating, is more effective because one bird examined on 29 January at 06:38 h. On 30 knows if the nestling is still hungry and can January, Willis found the pair of antshrikes adjust visiting rates efficiently. Thus, partial foraging in dense growth 20 m east among male abandonment may reduce predation the road from 16:12 to16:26 h. They were when there is only one of the normal two somewhat separate, but still foraging nestlings. In the gnateater case and probably together, as on January 21. He saw the female this one, the male did not help with the fledg- carry food across the road three times, and ling and molted earlier than the female. finally flushed the tailless young 0.5 m up in Snow (1963) suggested that female-only the understory; it fluttered to the ground and nest care may arise in fruit-eating birds vanished. On 24 March, both of the pair were because the male is not needed to feed young. near the nest area with an understory bird We accept this idea for single-nestling pihas flock, and a grown young female came out to (Willis & Oniki 1998), even though the young look at Willis in the edge growth, flicking her itself receives little fruit, but suggest that the tail slowly a bit before retreating with faint main reason is to lower nest predation or "fee” peeps to near the male, which was end- adult predation by reducing movement at the ing molt; the adult female was not far off. nest. We suspect that lower visibility to nest The gape angles of the young female were predators may favor partial male abandon- still a bit pale. The scrub understory was ment even in insectivorous antshrikes, and more visible because a few local farmers had that an insectivorous pair could bring too cleared the understory 5 m back on both much food for a single nestling, if our obser- sides of the road on 11 March to "let their vations of partial or complete male abandon- trucks pass”. ment are confirmed at other tropical nests with reduced nestling number. DISCUSSION Clearing the road edges was excessive here, including the entire nest bush, and In the Rufous Gnateater, Conopophaga lineata would have prevented our observations of a (Conopophagidae), we earlier (Willis et al. second case of male abandoning if done in 1983) recorded a case where a male stopped January. In 1997, other farmers forced feeding a single young after brooding stopped reopening a road through Iguaçu National and left the female to care for it alone. This Park in southern Brazil. Widening for 4 lanes was another case where one egg failed to on the São Paulo-Curitiba highway, which hatch. While the male antshrike here may passes through forest zones, recently led to have been more nervous than the female the state Instituto Florestal firing Willis doc- (both called and flicked the tail 27 January toral student F. Olmos (he suggested a detour after seeing the young handled, but later to avoid a site with rare Amazona vinacea, returned to the nest) it is more likely that he among other changes). Paving a road in the was not feeding regularly after brooding ornithologically important Broa Cerrado, stopped. near Rio Claro, engineers cleared long

93 GENERAL BIOLOGY stretches up to 20 m from the road in Santo. We appreciate comments by Lloyd Kiff unfenced cerrado, but to less than 5 m in and another reviewer, who improved the eucalyptus plantations nearby. Clearing 5 m manuscript. Publication nº 8 of the Institute back on either side of 3 km of reserve road, as for Studies of Nature. in Nova Lombardia, results in loss of 30,000 m2 or 3 ha of understory; 1–2 m each side REFERENCES would have been sufficient, as there are only a few cars and trucks per day. Meyer de Schauensee, R. 1970. Guide to the birds As human populations increase, people of . Livingston Publ., Wynne- want to widen roads, even through parks or wood, Pennsylvania. reserves. It would be better to put roads in Oniki, Y. 1975. The behavior and ecology of Slaty tunnels, or to cut roadside weeds only 1–2 m Antshrikes (Thamnophilus punctatus) on Barro back, as in human-occupied zones in the Colorado Island, Panama Canal Zone. Anais entire region of Santa Teresa, to save human Acad. Brasil. Cienc. 47: 477–515. effort, science and habitats. The subject mer- Snow, D. W. 1963. The evolution of manakin dis- plays. Proc. Int. Ornithol. Congr. 13: 553–561. its critical analysis. Willis, E. O., & Y. Oniki. 1998. One-parent nesting in Cinnamon-vented Pihas (Lipaugus lanioides, ACKNOWLEDGMENTS Cotinginae, Tyrannidae). Ornithol. Neotrop. 9: 129–159. We appreciate a grant from FAPESP Willis, E. O., Y. Oniki, & W. R. Silva 1983. On the (Fundação de Amparo à Pesquisa do Estado behavior of Rufous Gnateaters (Conopophaga de São Paulo) and logistical support from the lineata, Formicariidae). Naturalia, São Paulo 8: Augusto Ruschi Biological Reserve, Museu de 67–83. Biologia Prof. Mello Leitão and CNPq (Con- selho Nacional de Desenvolvimento Cientí- fico e Tecnológico) for our work in Espírito Accepted 9 June 1998.

94